1. Field of the Invention
The present invention relates to medical devices, and more particularly to catheters, cannulae, guidewires, endoscopes and similar flexible probe devices incorporating electroactive polymers for increased maneuverability and controllability.
2. Discussion of the Related Art
Coronary balloon angioplasty catheters are widely used in surgical operations for dilating blocked or clogged arteries. Such catheters utilize inflatable balloons, which are implanted at the site of a blockage in an uninflated state and are then inflated. The inflated balloon presses the blockage against the vascular wall in order to diminish the volume of the blockage and dilate the artery for reestablishing a more healthful blood flow. An intraluminal stent may then be implanted into the artery in order to permanently support the region that has been repaired by the angioplasty. A conventional method of stent deployment includes disposing the stent in a collapsed state above a deflated angioplasty balloon, inserting the balloon and stent into the vessel and inflating the balloon in order to expand the stent.
One concern with this device and similar devices is their flexibility and steerability, characteristics which significantly bear on the ease with which the device can be introduced and passed through the various channels of the body.
Accordingly, attempts have been made to produce a catheter, cannula, endoscope, or the like, which is readily insertable and maniputable for ease of advancement through body cavities or channels. One such device is disclosed in U.S. Pat. No. 4,543,090. U.S. Pat. No. 4,543,090 discloses a catheter comprising a tubular member having a proximal end and a distal end for insertion into the body. The distal end comprises a plurality of interconnected temperature activated memory elements. The memory elements are interconnected in such a way as to provide coordinated movement of the distal end. Essentially, each memory element assumes a first shape when heated to a predetermined temperature and a second shape in response to a force produced by one element acting upon an interconnected element. The memory elements are coupled to a controller for deflecting the distal end of the catheter in a plurality of directions to steer or aim it within the body.
U.S. Pat. No. 4,753,223 discloses a catheter assembly comprising an elongated, flexible, tubular body having a proximal end for connection to a power source and a distal end for insertion into a body. Rigid rings encircle the tubular body at axially spaced locations along the distal end. A plurality of shape memory wires extend between adjacent rings and are electrically connected to a control device and power source. By passing an electrical current through the wires in a controlled sequence, the tubular body may be steered through the body.
While each of these devices offers some degree of steerability, they do not provide for the coordinated precision movements required for a high degree of maneuverability.
Other attempts to provide catheters having distal ends, which, when inserted into a body are maniputable to advance the catheter through body cavities, include the devices disclosed in U.S. Pat. Nos. 3,674,014 and 3,773,034. U.S. Pat. No. 3,674,014 discloses a catheter that includes permanent magnets and employs a magnetic field to bend the distal end of the catheter. U.S. Pat. No. 3,773,034 discloses a catheter that includes fluid conduits and employs a fluid to bend the distal end of the catheter. Although these devices are steerable, they are somewhat difficult to control and manipulate.
Other work has focused on producing a catheter which is readily insertable while being effectively anchorable in a body cavity. For example, in U.S. Pat. No. 3,890,977, a catheter is disclosed in which the distal end is formed into a desired shape by using a material exhibiting mechanical memory that is triggered by heat. By heating the mechanical memory material, the distal end of the catheter is shaped to anchor the catheter within the body. However, the change in shape of the distal end in this device is essentially limited to a single direction.
The controllable intralumen medical device of the present invention provides a means for overcoming the difficulties associated with the use and operation of the devices as briefly described above.
In accordance with one aspect, the present invention is directed to a controllable intralumen medical device. The medical device comprises a flexible medical probe having one or more integral electroactive polymer actuators and a control module coupled to the flexible medical probe for selectively controlling the one or more electroactive polymer actuators.
In accordance with another aspect, the present invention is directed to a method for controlling the movement of an intralumen medical device. The method comprises integrating one or more electroactive polymer actuators into the intralumen medical device at one or more predetermined locations and selectively controlling the one or more electroactive polymer actuators to cause specific movements and states of rigidity in the intralumen medical device.
The controllable intralumen medical device of the present invention integrates a controller and electroactive polymers with flexible probe medical devices such as catheters, guidewires, cannulae and endoscopes to create a device capable of navigating through tortuous passages where precise control of the device is desired. By configuring the electroactive polymer material (typically strands) in various schemes and synchronizing material activation via the controller, the potential movement of the flexible probe that can be achieved would essentially be limitless. The combination of strand length, placement in or on the flexible probe, size and level of activation will determine the amount and type of movement possible. For example, the device may be made to bend in any direction in three-dimensional space. In addition, specific movements or states of rigidity may be achieved. For example, the device may be made to wiggle, slither, twirl, pulse, vibrate, rotate, expand or virtually be made to make any other movement or combination of movements. The device may also be made rigid along its entire length or in sections such that it may be guided through difficult to pass regions such as regions having tight stenotic lesions.
The electroactive polymer strands may be incorporated into or replace any portion of the flexible probe medical devices, including the tips, inner body, outer body or any other component of the devices to develop smart devices that can be controlled with a high degree of precision. In addition to making the device highly maneuverable as described above, the electroactive polymer strands may be integrated into various segments of the devices such that a section of the device expands in a manner which mimics a balloon in a balloon catheter or to expand an end of the probe to mimic an anchoring device.